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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Posted on 29 July 2010 by John Cook

A common theme expressed at Skeptical Science is that to understand climate, you need to look at the full body of evidence. To help people assess the evidence, NOAA have just published State of the Climate 2009. The report defines 10 measurable planet-wide features used to gauge global temperature changes. All of these indicators are moving in the direction of a warming planet.

Seven indicators are rising: air temperature over land, sea-surface temperature, air temperature over oceans, sea level, ocean heat, humidity and tropospheric temperature in the “active-weather” layer of the atmosphere closest to the Earth’s surface. Three indicators are declining: Arctic sea ice, glaciers and spring snow cover in the Northern hemisphere. Jane Lubchenco sums it up well:

"For the first time, and in a single compelling comparison, the analysis brings together multiple observational records from the top of the atmosphere to the depths of the ocean. The records come from many institutions worldwide. They use data collected from diverse sources, including satellites, weather balloons, weather stations, ships, buoys and field surveys. These independently produced lines of evidence all point to the same conclusion: our planet is warming."

Comments

That's a nice graphic! I'm going to forward it to a few friends of mine, along with some useful links. Sadly, I'm fairly confident of the response I'll get. :-(
Oh, and your first link points back to this page.

10 key climate indicators all point to the same finding: global warming is unmistakable.

Fantastic.

Now what are the 10 possible causes?

00

Response: When I wrote this blog post, I actually wrote a paragraph about causes but for the sake of focus and brevity, decided not to include it. But here it is for sake of completeness:

Now let me anticipate the immediate objection: "skeptics aren't disputing whether global warming is happening, just that humans are causing it". This is not the case. The bulk of the skeptic arguments I encounter these days are actually attacks on the surface temperature record, claims that glaciers are growing, disputes that the ice sheets are losing mass - generally attempts to cast doubt on any empirical data that indicates a warming trend.

So while there are many skeptics who agree that global warming is happening but question the cause, the bulk of energy spent by global warming skeptics is to attack the evidence for global warming. The most popular skeptic argument reported via the iPhone app since February is attacking the surface temperature record. So while I would love to move on from the issue of whether global warming is happening, the fact that the majority of skeptic activity is focused on this question prevents me.

Denial is a defense mechanism postulated by Sigmund Freud, in which a person is faced with a fact that is too uncomfortable to accept and rejects it instead, insisting that it is not true despite what may be overwhelming evidence (emphasis added). The subject may use:

* simple denial - deny the reality of the unpleasant fact altogether
* minimisation - admit the fact but deny its seriousness (a combination of denial and rationalisation), or
* projection - admit both the fact and seriousness but deny responsibility.

Just trying to give straightforward responses to what I thought was a straightforward question. Apologies if I misinterpreted your question (in retrospect I perhaps went a bit snarky with the "silly" reference at the end). Apologies, then, for the attempt at levity.

But as a short summary of root cause, for each point, my earlier comment still stands.

As far as John's post, I understand his need for clarity and brevity in his article, hence the not addressing the point-by-point attribution of cause to each indicator (which would require a separate post on each). But this has been done, both here and elsewhere.

Back to on-topic: Given that the world is indeed warming, what is to be done? Unless the discussion now turns to this, versus an endless rehashing and rebunking of memes, nothing will get done. We must lift our vision, for the weeds no longer matter.

It's a shame that they start talking about planet-wide indicators then deftly shift to NH sea ice. Cherry-picking? Global sea ice seems to have had little trend over the past 30 years as this Cryosphere Today graphic shows.

#6: I fail to see how an average value is determined from the isolated bits of data in "the plot". One of the nice things about the Law Dome ice core is that 280ppm is a very consistent value for the first 800 years. There's enough data to state that even the standard deviation of the CO2 concentrations is a consistent 2.8 ppm or less during that time period. This isn't a graph I made from these data (and I have made quite a few), but it gets the point across:

I question the significance of the ice-house/hot-house simplicity of climate reconstruction over geologic time. Unless you factor in the plate-tectonic setting during the relevant time periods, a simple hot/cold temperature graph doesn't tell the whole story. Same objection applies to the final graph you cite.

As far as a relationship between CO2 and temperature, see below:
Again, not my work, the source is shown and here is a link to the host page.

#5: Hang around a while, you'll see all three styles of denial in action. What is nice about this site is that at least most people remain polite.

I've only read one section in the full report so far, Ocean Heat Content OHC (page S56 onwards). Some fasinating images of the patterns of changing heat content of the oceans. The text seems to primarily concern itself with the regional nature of the OHC anomolies and how that's changed over time.

It seems to spend a long time connecting this to regional climate features such as NAO and PDO. Can we be sure that the overall change in OHC from 1993-2009 truely is a sign of a warming world or just a measure of the shift of warmth around the oceans? Or maybe more likely a combination of both. How do we prise apart the two features in the data? (if they exist)

You are linguistically correct in that Arctic sea ice by itself would not be a global indicator. It is directly reflective, however, of a global disequilibrium response to a planetary forcing due to rising CO2 concentrations from fossil fuel emissions and other, subsequent, positive forcings. And in that regard a significant indicator of global climate change/warming.

Using the Cryosphere Today graphic for global sea ice trend is a bit of a straw-man argument. That graphic focuses on global area. No considerations are given to extent or thicknesses/volumes.

As the NOAA report makes clear, Arctic sea ice trend IS in decline. Multi-year, thicker ice, is almost gone, replaced with seasonal ice, resulting in greater seasonal melt oscillations. Polar amplification of warming due to climate change will keep it moving in that direction as well. Pray for a continued weak Arctic DiPole this year and next to slow the export of the remaining ice out the Fram Strait...

For various reasons (winds, ozone, weather), portions of the Antarctic sea ice are in stages of decline, stasis or growth, with a net inconsistency overall.

John's article doesn't even mention the net multi-gigaton mass loss of both the Greenland and Antarctic ice sheets themselves, as documented in the NOAA report. Again, the need for brevity in a summary article. But that's why he included the link to the source report.

And so as you say, "Back to on-topic: Given that the world is indeed warming, what is to be done? "

It truly would be great if we could, in an instant, stop all CO2 production, and sit back and see if in fact CO2 in the atmosphere stabalizes and/or reduces.

But we can't. That's the reality.

Since the advent of the industrial revolution the so called western society, principally Europe and North America has been getting very rich by pouring CO2 into the stmosphere, and compared to most of the third world have a very high standard of living, I’m Australian. And if it turns out to be fact that it’s CO2 that is causing the temperature increase then we have been inadvertently ‘engineering’ the atmosphere. Surely if we can ‘engineering’ the atmosphere accidentally, then with all our wealth and science resources we can ‘engineer’ a correction, without having to impede the economic progress of the third world, in particular China and India. They are not going to reduce their CO2 production anyway.

There is lots of ways we can accommodate CO2 increase. Here’s one idea. Isn’t it a fact plants need CO2 and if you increase CO2 their growth becomes prolific. So why not green the Earth? As the Earth’s atmosphere and seas warm there will be lots more precipitation, all very condusive to turning the Earth into the fabled “Garden of Eden.” But what of coastal cities? We can dyke them. If the Netherlands can do, I’m sure the rest of the world can. Plus per tonne of carbon, forestry is the cheapest method of reducing CO2 polution. Its about $10.00 per tonne.

Do you know where the Sootese temperature record for the past 600 million years comes from?
I am aware of the Hansen reconstruction of the past 65 million years:
http://www.columbia.edu/~mhs119/Storms/Storms_Fig.18.pdf
It does not corollate with the Soteese graph at all over this period.

I'm not sure why folks are using the graph HR points to as some sort of evidence of stability. Even by eyeball it's got a downward trend, and in any case as others have pointed out it's for global sea ice. As has been pointed out here on SkS, Antarctic sea ice has increased in extent according to expectations though it may seem counter-intuitive.. The fact that the graph -still- shows a declining trend is no cause for celebration, it only helps illustrate how dramatic loss has been in the Arctic.

Miekol, New Orleans is nice and green, with mild winters, is at or even below sea level and has ample vacant properties available for little money. Perhaps you should put your hypothesis to the test and try moving there.

'Global warming' happens all the time because the sun continually warms the Earth-so it is obvious that 'global warming' is unmistakeable', this has been going on since the sun started shining. (The question of natural versus human rate of temperature change, is a question which should at least be stated less ambiguously/more correctly).

How's this for a theory: The way climate change terms often have multiple meanings half explains why they keep finding 'evidence' for their position. One only has to look at the sun and see evidence for 'global warming', so to speak, every day.

We agree that the industrial world has indeed built its standard of living and society on the backs of CO2 emissions. But Business As Usual got us to where we are today and has Become the Problem. And cannot continue.

Given the response lag time of both human nature (with its endless ability to procrastinate) and the lag built into the disequilibrium response of the climate to the forcings imposed upon it by CO2 (30-40 years; we are just now realizing the temperature response imposed by the carbon slug of the 70's and 80's injected into our carbon cycle) there is perhaps nothing mankind can do to avoid a severe coming disruption to our food production chain.

Note the use of the word avoid. Opportunities still lie before us in terms of mitigating the future deleterious effects a warming world has in store for us. Michael Tobis, over at Collide-a-Scape (summarized by Lou Grinzo on his blog) summarized it best:
"...carve out a “middle ground” where we spend some effort on a more or less inconsequential improvement on the carbon imbalance. Surely that’s better than nothing?

Well, no. Not consequentially, no, it isn’t.

The correct long-target for CO2 emissions is zero. The correct short-term target is negative. That’s not radicalism or idealism or romanticism or folly. That’s just the facts."

It will take a comprehensive, worldwide, species-wide response to the crisis we find ourselves in. And unless that response is one of ZERO CO2 emissions for the next 30 years (at which point our climate should stabilize at about Another +1.8 to +2.4 degrees C relative to 2010 temperatures) our way of life is TOAST (no pun intended) anyway.

Carbon Capture Sequestration and other discussed geoengineering options in the literature today hold various promises, but none to help us NOW.

Reforestation efforts are a mixed bag. The literature abounds in studies on this. An attempt to summarize: Some short-term gains can be achieved, but once a forest reaches maturity it goes into a relative CO2 balance intake-vs-emission-wise. At the expense of planting most of the world's grasslands and a good portion of its croplands. Assuming the grasslands don't turn to dust in the face of unrelenting shifts in rainfall patterns...or washed away by an atmosphere now holding an extra 4% moisture in its fuel tanks (equivalent to the volume of Lake Superior on my doorsteps). And by itself, nothing to help us NOW.

I'm not trying to be a nay-sayer wet blanket here. All this discussion of potential options has merit. But in terms of realizable, actionable near-term policies to implement (as a species), we've got nuttin'. Time is a more precious commodity than we realize. And we have little left.

miekol wrote :"There is lots of ways we can accommodate CO2 increase. Here’s one idea. Isn’t it a fact plants need CO2 and if you increase CO2 their growth becomes prolific. So why not green the Earth? As the Earth’s atmosphere and seas warm there will be lots more precipitation, all very condusive to turning the Earth into the fabled “Garden of Eden.”"

You had better read a few pages on this site for more information on that, especially :

#6 again: One of the data sources for 'The Plot' is Kouwenberg etal, 2005 (abstract only, but I have the full pdf).

Omitted from 'The Plot' are "four CO2 minima of 260–275 ppmv (ca. A.D. 860 and A.D. 1150, and less prominently, ca. A.D. 1600 and 1800)." That pre-industrial 305ppm average has a serious case of cherry-picking.

Kouwenberg reaches the opposite conclusion vs. 'The Paper': "Because the CO2 variation also shows similarities with terrestrial air temperature trends in the extratropical Northern Hemisphere regions — which are the areas most sensitive to global warming — it may be hypothesized that throughout the last millennium, CO2 could have served as a forcing factor for terrestrial air temperature." There is even a graph (Figure 3) showing good correlation between these stomatal frequencies and ice core CO2!

Interestingly, Kouwenberg shows up on denier blogs (here's one) as 'peer-reviewed evidence' against CO2 forcing -- which is exactly the opposite of paper's result. Makes you wonder how many other of their 'sources' are flat-out mistakes like this one.

Now, in v2.temperature.inv there is a station 42572503001 NEW YORK CENTRAL PARK (it's close to Belvedere Castle). You can look up for example average temperature at this site for May, 2001 and find 17.6°C. So far so good.

It says average mean temperature was 17°C. But we can go a little bit further. Down that page there is a mean temperature for each day of the month. Their sum divided by 31 (number of days in May) yields 16.84°C.

The thing is Weather Underground also have all the individual METAR records for that place and period. You can look them up by clicking on a particular day in the list, e.g. May 19, 2001.

Therefore the correct number is 16.84°C and not 17.6°C as claimed by the United States Department of Commerce.

If even values in the raw dataset can be adjusted upward by up to 0.76°C (1.37°F), a century scale trend of the same order of magnitude is absolutely meaningless. When doing science, details and facts do matter, while the big picture or independent, multiple lines of evidence can only serve as heuristic tools.

That is, they can help find true propositions, but they prove nothing. Each and every proposition found that way has to be subjected to a painstakingly detailed scientific verification process. That's how it is supposed to work.

When doing science, details and facts do matter, while the big picture or independent, multiple lines of evidence can only serve as heuristic tools.

So all these little pictures that go together to show a big picture of unequivocal warming, yet your argument elevates the contrarian practice of cherry picking as more valid. Incredible. The way you put it you think we'd expect to see lots of contradictory evidence that as a whole could be misinterpreted to show spurious alarming anthropogenic global warming. However the word spurious only makes it due to your logical contortions and one-eyed view of the supporting science, logic and philosophy.

Looking at the finality of these combined data-sets, something occurs to me: those of us who spend any time commenting on these forums need to remember that the vast majority of people aren't interested in the sort of climate change arguments we have. There's a danger, I think, that we mistake the heat and noise of blog-science for what's happening out there in reality.

Most people, I believe, would see the evidence presented here and conclude that, yes, the planet is warming. Obviously, undeniably. I worry that we need to find a better way to channel our energies: blog arguing can feel 'important' when perhaps it isn't. Question, then: given that, actually, most people would accept the overwhelming evidence, how might those of us accepting of the science best spend our finite time? We *could* spend an infinite amount of time arguing with contrarians, about the scientific equivalent of whether the data shows we're heading to winter or summer. Perhaps we need to not let ourselves get drawn into that quite as much any more. Contrarians have made quite enough rope to hang themselves with. We still need to argue, and amazing blogs like this will always be needed. But perhaps we need to withdraw some of the oxygen of attention contrarians still get.

The battle is about doubt, not science. That battle isn't going to be won arguing with people still harping on about particular weather stations, months after that line of argument was shown to be nonsense. It'll be won convincing the wider public that any doubts they may have harboured are (sadly) misplaced.

Saying someone who disagrees with you or with some aspect of what you are saying is a very comfortable argument - indeed, it's an argument to which no response is possible.

Denial is not the sole province of the 'sceptical' community.

All of us can go into denial. All of us cherrypick facts to suit our point of view. We sometimes call this selective recall. The AGW community is no exception to this universal human tendency.

Earlier this year, we were hearing about the record ice melt in the Northern Hemisphere. Now that NH ice seems to be holding up (indeed firmly back within two standard deviations of the mean over the last thirty years), we're told that it's not sea ice extent but rather sea ice volume, quality, or whatever metric comes to hand. Meanwhile, sea ice extent has continued its increase in the SH.

And yes, I'm aware that the Greenland ice cap and Antarctic ice cap may be losing mass. I do my best not to cherrypick.

We frequently hear about record high Arctic temperatures in the Arctic when in fact our instrumental record for the Arctic is very slim and calls for enormous extrapolations.

Could this just possibly mean that some negative feedbacks or forcing might be coming into play? It would be nice if this proved to be the case - certainly, a better outlook for the planet.

I don't pretend to know who's right at least on the sea ice question.

I've held off to date on commenting on the appropriateness of long range psychiatric diagnoses by unqualified practitioners. However, repeated references to 'denial' with references back to the psychiatric literature make me grumpy.

Firstly, what is the fascination with GeoCraft.com among Sceptics. I have had the last graph you refer to pushed at me dozens of times by sceptics. Always associated with the question, implied or not that if CO2 varies so differently with Temp well in the distant past well....?

Addressing that in a moment, I would first like an answer to why Geocraft.com attracts sceptics like Pooh bear to Honey. The site is self-described as belonging to a Monte Hieb.

www.takeonit.com lists Monte Hieb as:

"Monte Hieb is the author of several popular web pages skeptical of Anthropogenic Global Warming, serving as a evangelist for the viewpoint (he does not state his qualification in climatology or a related science). He is an employee at the West Virginia Office of Miner’s Health, Safety, and Training. "

So what is the fascination with Monte Hieb?

Now to the graph, yet again; I am getting tired of repeating this one.

This graph, and better versions of it are available elsewhere, is not the full answer because it doesn't take into account the fact that Solar output was lower in the distant past. The world needed more CO2 to compensate for the cooler Sun.

If your question was honestly meant then I suggest you read some of John's posts here. A Search for 'Royer' will turn up a number of them. One is here at http://www.skepticalscience.com/CO2-has-been-higher-in-the-past.html.

Then you might like to look at Wiki, looking for the 'Faint Young Sun Problem' and working from there.

However, if your 'question' was a little more disengenuous than that (and citing Monte Hieb implies that) then ScepticalScience was probably the wrong site to 'ask' that question.

I know all too many people who have reported precisely these symptoms and after about ten or so visits to the emergency room resulting in normal ECG, cardiologist reviews with normal findings, and normal stress test results eventually find their way to my office.

Panic attacks and generalised anxiety disorders are also very common and require a different line of treatment to ischaemic heart disease. Indeed, repeated visits to emergency rooms in such circumstances can reinforce panic symptoms.

Moreover, you can have both panic disorder and ischaemic heart disease at the same time. It's important to work out whether a patient's symptoms are due to one or the other (or possibly both).

I would certainly be urging someone who reported these symptoms for the first time particularly after exertion to be going to the emergency room.

However, to bring this back on topic (ie, AGW), I'd be suggesting that while there's lots of evidence the world is warming and that human caused CO2 emissions contribute substantially, the questions around the robustness of the paleoclimate record and the reliability of the current instrumental record are important in determining our response.

To go back to the medical analogy, do you take a Valium and practice deep breathing/ relaxation or do you give sublingual glyceryl trinitrate and put the patient on the urgent list for a stent? Indeed you might do both.

#25kdkd at 18:17 PM on 29 July, 2010your argument elevates the contrarian practice of cherry picking as more valid. Incredible

It's not cherry picking, it is called reality check. A very different kind of activity.

We have 67 overlapping months between GHCN and Weather Underground for Central Park. After September, 2006 GHCN has dropped this station and before March, 2000 Weather Underground has only fractional data for the site. Anyway, adjustment statistics with 0.1°C bins looks like this for the period:

Remember. It is not proper adjustment (if it were, it would have supposed to go into v2.mean_adj), it's just some undocumented fiddling. The statistics does not look like measurement error for sure.

If things like this are allowed to be done to the raw dataset even at a single station, a full scale audit is warranted indeed. You can't deny that in good faith.

On the other hand, you can't expect me to do the full job either in my spare time when there are payed government employees for this very purpose.

Anyway, I'll do my best, but any help would be appreciated. As far as I know no one has looked into the adjustments done to raw GHCN values yet.

I have already downloaded data from Weather Underground for Canada and Alaska the other day. As time permits, I'll run the check for those sets and report back with the results.

I have been waiting for this material to be released for six months. The graph I prefer is the one on page 26-27 of the report. I can tell you having written the glaciers chapter Page 49, and provided the glacier data for the graph 26-27, that there is an immense amount of peer review of this material.

00

Response: I presume this is the graph you're talking about:

That page showing time series of eleven different indicators is a great resource. I may do a follow-up post focusing on the content from that page. Thanks for your comment (and your work on the NOAA report).

BP, let me get this straight. You see a difference in reported temperatures for a NYC station between GHCN and Weather Underground. You then conclude that this must be "undocumented fiddling" by GHCN. Do I have that right, or am I missing something?

"Earlier this year, we were hearing about the record ice melt in the Northern Hemisphere. Now that NH ice seems to be holding up (indeed firmly back within two standard deviations of the mean over the last thirty years), we're told that it's not sea ice extent but rather sea ice volume, quality, or whatever metric comes to hand. Meanwhile, sea ice extent has continued its increase in the SH."

Where are you getting all that information from ? Some of it sounds as if you are getting it from NSIDC, but anyone looking there would not see "NH ice...holding up (indeed firmly back within two standard deviations of the mean over the last thirty years)". Have a look at the blue line there.

Also have a look at these comments there :

Ice extent remained lower than normal in all regions of the Arctic, with open water developing along the coasts of northwest Canada, Alaska and Siberia.

As of July 15, total extent was 8.37 million square kilometers (3.23 million square miles), which is 1.62 million square kilometers (625,000 square miles) below the 1979 to 2000 average for the same date...

None of the NH graphs at Cryosphere Today seem to back you up either.
Where did you get your information from ?

As for the SH, what do you mean "sea ice extent has continued its increase" ? 'Continued' from when, to what sort of 'increase' ?

Chriscanaris #28 wrote: "Now that NH ice seems to be holding up (indeed firmly back within two standard deviations of the mean over the last thirty years)"

That doesn't match up with the data I'm seeing;

Extent is a little above the 2007 results, which were the lowest ever recorded, but still well below two standard deviations from the average (the grey shaded region). The ice is also both thinner and less concentrated than it was in 2007... making it still entirely possible that we could see a new low extent this year depending on weather over the next month and a half.

In any case, focusing on volume isn't some 'dodge'. Volume is the amount of ice. If we want to know whether the ice is increasing or decreasing what we are looking for is the change in volume. Unfortunately, we don't have precise data on the total volume right now because IceSAT went offline and Cryosat II data is still being analyzed. Which is where proxies like extent get pulled in.

From these simple formulas it can be seen that Extent differs from Volume by two variables, and thus is not a particularly accurate proxy. It's just comparatively easy to measure.

BTW, even though Cryosat II data hasn't been released yet the less precise measurements of sea ice area, concentration, and thickness from other satellites show steep declines this year. Thickness and concentration are both well below where they were in 2007 and as a result ice volume is clearly at an all time low, well beyond the uncertainty range of the estimates.

FWIW, I have close to zero interest in spending my time today trying to track down the cause of a difference between the reported GHCN monthly mean for a particular station and the average of the Weather Underground daily means for that station. That will be a complicated project because the WUnderground data come from daily METAR reports while the GHCN monthly data come from monthly CLIMAT reports.

I do find it interesting that out of the universe of possible explanations, BP jumps immediately to the conclusion that it must be malfeasance ("undocumented fiddling") by GHCN.

Taken literally and if someone wanted to waste a lot of time going over existing science, then your comment might be valid.

However statistically it would be very unusual to have different reasons for all 10. That is the point of publishing them.
The hypothesis is validated by all 10 occurring at the same time.

What you should be doing is putting together a hypothesis to explain why all 10 are happening and submit it. It isn't the onus of scientists to come up with an alternative theory if they don't think there is one.

Chriscanaris - " Meanwhile, sea ice extent has continued its increase in the SH."

See argument 105. It's a logical fallacy that the Arctic and Antarctic sea ice would behave the same in a warming world, as indeed some early climate modeling predicted the asymmetry.

Chriscanris - "And yes, I'm aware that the Greenland ice cap and Antarctic ice cap may be losing mass. I do my best not to cherrypick."

Cherry picking is what one does in order to mislead. Notice how the contributors here put it all into context?. And the Greenland and Antarctic ice sheets "are" losing mass, not "may be", that sounds is bit misleading don't you think?.

I agree, one should ask questions first rather than leaping to conclusions. One should also be very precise in the formulation of one's questions and answers, to prevent needless confusion.

1. Is there a difference? (yes)
2. Is it documented? (no)

We don't know that. You initially claimed that the difference in adjustments between US and non-US stations in GHCN was "undocumented" when in fact a few seconds with Google revealed that the difference is widely discussed, including in the primary paper about GHCN (Peterson & Vose 1997).

3. Does GHCN v2 have the original METAR records? (no)

GHCN-Monthly is not derived from METAR records, it's derived from CLIMAT records.

4. Does Weather Underground have them? (yes)

Yes, the daily data at WUnderground are derived from METAR.

This suggests that you're launching into a comparison of, if not apples and oranges, perhaps granny smiths and macouns.

7. Are the magnitude of adjustments comparable to the trend? (yes)

That's not really a relevant question, now is it? Assuming for the moment your claim that there is an "adjustment" (proof of which is not in evidence) ... as long as there isn't a trend in the adjustments the adjustments won't affect the trend (over long enough periods of time).

8. Are adjustments supposed to be done to raw data in GHCN? (no)

Note that you haven't yet actually established the existence of an adjustment by GHCN.

I'm not really interested in quibbling about the the surface temperature record. As far as I can see as an interested observer there is no significant difference between the independently derived temperature records.

What I am interested in is the logical contortions that you have to use to ignore the big picture, choosing instead to focus on, and magnify out of all proportions, the perceived uncertainties. The key point I made that you have chosen not to address (I detect a pattern here) is:

"The way you put it you think we'd expect to see lots of contradictory evidence that as a whole could be misinterpreted to show spurious alarming anthropogenic global warming"

The way you present your position that the big picture is unimportant, this is the only logical interpretation I can think of as to why you would take this view. It is also interesting that you chose not to address this aspect of my attack on your position.

BP, the GHCN temperature data are in close agreement with a separate surface data set AND the satellite temperature data AND proxy temperature data sets.

In short, if you really must go on with the conspiracy theories about how the three GHCN based temperature sets have all been faked then you're going to need to explain how those other sources have ALSO been faked.

Thanks for this fine graphic. But gosh how I wish I could share this with all the naysayers I know. I used to post comments on global warming at my Facebook page, but sooooo many there just refuse to admit that it's happening that I stopped posting anything on GW there altogether. But I am grateful for what I see here - at least I stay informed. I hope the naysayers will come 'round some day though I fear that won't happen until it's far too late for them to do anything but suffer through they helped to cause - or even worse to know what they did will adversely affect the lives of their kids, grandkids and great-kids, etc . . .

An obeservation. It seems to me, from a layman's viewpoint, that sea ice EXTENT is a function/indicator of WEATHER -- thin ice forms and melts relatively quickly due to the ambient temperatures in an area over quite a short time period.

On the other hand sea ice THICKNESS is a function/indicator of CLIMATE -- thick ice hangs around for a long time with its thickness changing by only a relatively small amount due to the weather it experiences.

Overall though it's only variations in ice VOLUME that can evidence the trend to a colder or warmer climate.

That's not to say that sea ice extent is not useful -- when averaged over years, its variations are the most easily-observed sign that the climate might be warming (or indeed, at other times, cooling) -- but to give any priority to extent data over volume data would be illogical ('cos it's only half the story).

I'm also bearing in mind that (I think I'm correct in saying) it's also only recently that reliable volume data has been available, which might explain why it could appear that scientists are now shifting their position.

Actually, the Central Park station BP is interested in is apparently a USHCN station. I really haven't looked into the exact process by which data go from the actual station into the USHCN database and then from there into the GHCN database. Suffice it to say that this is a complicated subject (is the monthly average of daily data created at the station, at USHCN, or at GHCN?). If someone else wants to get into the weeds of this process, they're welcome to, but I will definitely not have time to spend on this right now.

BP you may find this link interesting. It relates to the differences between Weather Underground data collection and GHCN. To cut ot the chase, Weather Underground uses METAR data and GHCN doesn't. Anthony Watts(!) noted that there are problems with the METAR data.

A new study says that phytoplankton in the oceans have decreased by 40% since 1950. We'd better pray this is erroneous because if it isn't we're looking at a massive decrease in human population within this century.

Of course it would be nice to go back and check old records, but unfortunately there is not much genuine old temperature data online. I may visit Hungarian Meteorological Service and have a talk with them (Debrecen has data since 1853, Budapest from 1780).

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Moderator Response: This level of detail and sheer space consumption does not belong on this thread. Put future such comments in the Temp Record Is Unreliable thread. But if you post too many individual station records, I will insist that you instead post summary statistics.